I have an x32 using 2 S-16 stage boxes and 8 P-16 monitors on stage. We have had the system for 1.5 years and the only real regular complaint is that the in ear system is just not loud enough to make the artists happy. They have used a system in a different venue recently that was much louder and now they are asking why isn't ours.
I have always though that this issue might be related to gain staging and that the sound tech who set up our system, did so in a way that causes us to gain down all of the channels to get the house mix right which is lowering the volume of the in ear mix as well. If this is the case, I would think that if we lowered the output of the main amps, then gained the channels back up to set the room, the in ears would then be louder.
In case your in ear system stems from the 8 p16m's and that's what you are talking about...There are 3 volume 'layers' with the p16m.
First volume layer is the 16 ch's along the bottom, select each ch and use the volume knob.
*Second volume layer is the 'Main' button, middle row far left...Select that button and then adjust the same volume knob used for the individual ch's. All the ch's on the bottom will now ALL get a lot 'hotter' overall and may all need adjustment downward, especially if most of the individual ch volumes were being set at a high level to compensate. This is the one layer that OFTEN gets overlooked.*
Third layer is the top row, far right where it says 'Level' which is the final output level, and used in conjunction with the limiter. That may also need adjustment if your "main" button was low. They are capable of getting VERY loud and why they added the limiter!
Between those 3 settings any user should be able to get their P16M plenty loud enough.
I would assume (again IF using the P16m's) that all the p16 ch's were set at pre eq so any FOH changes did not effect the monitors but either way the volume bit above will adjust volume individually for each user. In the event you are using another in ear system along with the P16M's...sorry to take off in the wrong direction!